This plugin overloads model.save to the following signature: model.save([skipValidations], cb). With out a boolean as
the first argument, the behavior is identical to modella's default.

With the additional flag, it will skip validations. Optionally if SaveInvalid.invalidAttr or SaveInvalid.completeAttr is set, an invalid model will have
that attribute persisted as well. This is useful so that you can only query for valid models. E.g: